bin/gapps: Print usage on argument error.

Author: nishantjr

bin/gapps

@@ -60,5 +60,6 @@ if (program.args.length == 0) {
 if (err) {
     var p = require('process')
     console.log(err)
+    program.outputHelp()
     p.exit(2)
 }

t/t010-basic-cli.js

@@ -27,6 +27,7 @@ tlib.test('help', (t) => {
 tlib.test('no command fails', (t) => {
     const cmd = tlib.spawn(t, './bin/gapps')
     cmd.stdout.match('No command specified\n')
+    cmd.stdout.match(/Usage:/)
     if (tape_spawn_fixed)
         cmd.fails()
     cmd.end()
@@ -35,6 +36,7 @@ tlib.test('no command fails', (t) => {
 tlib.test('bad commands fail', (t) => {
     const cmd = tlib.spawn(t, './bin/gapps rubbish')
     cmd.stdout.match('Bad command specified\n')
+    cmd.stdout.match(/Usage:/)
     if (tape_spawn_fixed)
         cmd.fails()
     cmd.end()